A sliding member of a hydroelectric generator is generally lubricated with oil, but application of a water lubricated bearing is demanded in consideration of environmental concerns of contamination of river by oil spill.
It is disclosed that a sliding member of a water lubricated bearing has a base material made of a metal material, an intermediate layer of a porous structure joined on the base material and made of a metal material, and a sliding layer formed on the intermediate layer and made of a resin material.
In an intermediate layer of a sliding member, a plurality of spherical members made of a metal material is formed on a main surface of a base material to be joined to the main surface, constituting a porous structure. A shape of a hole of the porous structure constituted with the plural spherical members is anisotropic.
When a resin material of a sliding layer is to be filled into the hole, filling corners of the hole is difficult and a part into which the resin material is not filled is sometimes left as a gap in the hole.
In an underwater environment, if the part (gap) into which the resin material is not filled exists in the hole of the porous structure of the intermediate layer, water enters the gap and corrosion occurs from the gap as a starting point (gap corrosion). There is a problem that a mechanical property deteriorates with time due to gap corrosion when a sliding member (bearing member) is used under water for a long time.